The present invention relates generally to dynamic balancing of rotating shafts.
Rotating shafts may be balanced to reduce noise and vibration created when the shafts are out of balance. For example, a prop-shaft (drive shaft) in an automotive vehicle may be balanced in order to reduce the noise and vibration produced during vehicle operation, making the vehicle environment more pleasant for vehicle occupants.
Typically, detecting dynamic shaft imbalance is accomplished at a single rotational speed, with the shaft having to meet an imbalance specification at that speed. Occasionally, after the detection at a first speed, the shaft may undergo an audit at a higher speed to meet a second imbalance specification for that higher speed. However, when the shaft is corrected for any imbalance at the higher speed, the imbalance may be deteriorated at the lower speed (where the imbalance at the lower speed had been previously corrected). For an automotive vehicle, it may be desirable to provide the lowest possible imbalance at more than one rotational speed.
For example, an automotive vehicle may exhibit a body cavity resonance that is excited by a rotating driveshaft at a first rotational speed. It may be highly desirable to reduce the imbalance at this first rotational speed to reduce vehicle interior noise that may bother occupants. For this same automotive vehicle, it may also be highly desirable to minimize the driveshaft imbalance forces imparted to the vehicle power plant at a second rotational speed, which may be a speed that occurs while cruising on a highway. Minimizing the imbalance forces at this second rotational speed may help, for example, to maximize the durability of a transmission case structure.